Swiss cheese has holes in it: Do you know why?
Imagine this: You are alone at home and you are craving a sandwich. You go to the fridge and take out two slices of bread, maybe some salami, a layer of crunchy and tasty veggies, a bit of pickle, and a spoonful of mayonnaise. Wait, perhaps you are forgetting the most important ingredient, cheese. What is your go-to option? American cheddar, Italian mozzarella, or good old Swiss cheese?
Well, if Swiss cheese is your answer, then here comes a question: Have you ever wondered, why it has holes in it? Did the manufacturers design it for convenience? Or is it something else? Hold your thoughts. Let us find out the answer for you.
There’s science behind these holes
You must be wondering what science has got to do with the holes in your favourite cheese. Well, it was indeed a mystery for centuries, until in 1912 a chemist at the U.S. Department of Agriculture called William Mansfield Clark published his hypothesis behind the holes in Swiss cheese.
Turns out, just like all other cheeses, Swiss cheese, which comes with a distinct yellowish colour and tangy taste, is produced by adding specific bacteria cultures to milk. This, in turn, leads to a chemical reaction.
Now, Clark posits that the particular bacterium used in the making of Swiss cheese, called Propionibacterium freudenreichii subspecies shermanii or P.shermanii in short, produces carbon dioxide when exposed to the required temperature 70°F. This in turn forms gas bubbles inside the cheese. Can you guess what happens next? The gas bubbles make round openings in the cheese, which are popularly called ‘eyes’ by the cheesemakers worldwide. Think of it like this. When you try to blow a bubble while chewing a gum, the air you blow puts pressure into the gum making a circle. But it pops when the pressure falls, as temperature remains unchanged. However, in the case of Swiss cheese, the CO2 bubbles don’t pop as the cheese is cooled down, thus maintaining the required pressure. As a result, the hole, once formed, stays in place.
Holes or hays?
Throughout the 20th century, Clark’s theory remained unchallenged. However, in the 1990s, researchers found that Clark did not tell the (w)hole story. During the late 20th century, it was observed that Swiss cheese was turning blind. Yes, you read that right. When the holes (referred to as eyes) in Swiss cheese were vanishing, the cheesemakers started terming it as ‘blindness’. But what led this cheese lose its ‘eyes’? The answer is hay.
For long, scientists used to believe that CO2 gas bubbles in Swiss cheese directly led to the formation of the holes. But a 1990 research threw light on a brand-new information. It was found that the holes weren’t the direct outcome of these bubbles. Instead, they used to be created when bubbles formed around hay dust particles, found in milk packages.
Keeping hay at bay
Cheesemakers across the globe have now modernised their cheesemaking techniques. Traditional buckets, packages and barns have been replaced with modern processing centres that now have sealed milking machines. This significantly reduced the presence of hay particles, in turn the holes in Swiss cheese. So, the next time you have an exceptionally holey Swiss cheese, know it has hay.